1. Field of the Invention
The present invention relates generally to solvent extraction processes for recovery of metal values from aqueous solutions, particularly aqueous solutions containing copper and iron, and which may also contain chloride, and more particularly to an improvement in the process which provides increased copper to iron ratios in the loaded organic extractant phase. The improvement comprises washing the loaded organic extractant phase prior to stripping of the copper values therefrom with an aqueous acidic scrub containing at least a portion of electrolyte.
2. Statement of Related Art
U.S. Pat. No. 4,582,689 describes a solvent extraction process from which copper is extracted from aqueous leach solutions using hydroxy acryl oxime extractants in which enhancement of copper/iron selectivity was achieved by adjusting the retention time for mixtures of aqueous feedstocks and reagent containing organic phases in the mixer-settler stages of multistage extraction systems. A general description of a solvent extraction process is found therein.
Process Metallurgy 1, G. M. Ritcey and A. W. Ashbrook, Solvent Extraction: Principles and Applications to Process Metallurgy, Parts I and II, Elsevier Scientific Publishing Company, 1984 and 1979, respectively, describe solvent extraction principles and applications. Reference to washing or scrubbing of the loaded organic phase and minor leach solutions and extraction circuits to which the present invention may have applicability can be found on pages 2-5 and 62-63 of Part I and pages 12, 13, 226-229, 290-293, 312, 313, 538 and 539 of Part II.